The invention relates to a reservoir for a power steering system, for a vehicle, of the type including an engine-driven pump circulating oil through a steering-wheel-operated hydrostatic steering unit which communicates with a double-acting hydraulic piston-and-cylinder assembly and can function in known manner as a manually-operated emergency steering pump if its supply of oil from the engine-driven pump fails, the reservoir being adapted to communicate with a port of said unit and with the inlet of the engine-driven pump.
The object of the invention is to ensure that sufficient oil to enable the hydrostatic steering unit to function as a manually-operated emergency steering pump is retained in the system in the event of fracture of the pipework connecting the outlet of the engine-driven pump to the inlet of said unit.